Several devices have been used to provide images having different depths of field. U.S. Pat. No. 4,306,768, issued to Egging, teaches the creation of multiplanar images. Egging's device includes a primary image generation chamber that is observable along a viewing axis extending through a viewing port. The primary image generation chamber is divided into a plurality of cells each containing an image source such as a portion of a video display tube screen or an actual physical object.
The viewing axis extending through the viewing port is substantially at right angles to the video display tube screen; and the image from each portion of the screen is reflected along the viewing axis by a light transmissive, two-way mirror disposed in the primary image generation chamber at an acute angle to the axis. An image from each of the video display tube screen portions is reflected by one of the mirrors and can be observed through other mirrors between the reflecting mirror and the viewing port. Any actual physical object disposed along the viewing axis can be observed through mirrors disposed between the object and the viewing port.
The cells and mirrors can be arranged to provide images having desired depths of field and can be selectively movable to impart an illusion of movement to an image generated at a fixed source. Additional mirrors disposed at a slightly different angle may be used to create additional images.
Egging also discloses a secondary image creation chamber containing fixed or movable shelves. The shelves are also disposed substantially at right angles to the viewing axis extending through the viewing port. Images created at the shelves are reflected along the viewing axis by another light transmissive, two-way mirror disposed in the primary image generation chamber at an acute angle to the axis, images created by the video display tube being observable through this mirror at the viewing port. The shelves are of increasing widths in proportion to their relative distances from their associated mirror so that images created at display portions of more distant shelves are observable past less distant shelves.
The Egging device, while appearing to represent an efficient multiplanar display system for applications requiring images of moderate size, is limited with respect to the total image size it can display. The primary limitation of image size is dictated by the maximum practical size of its video display tube. Even a large tube would provide relatively small images because its screen is divided into separate cells. The number of images would also be similarly limited.
Even if the tube were to be replaced by a separate video display tube for each of its cells, the disclosed construction of the device would require that the housing be impractically deep, which would make it unsuitable, for example, for large wall displays. Such a display would be costly to build, would be unwieldy to transport and would infringe on premium available display room space.
The Egging device requires a certain minimum difference in the depths of field between successive images. Again, an enlarged version of the device for use as a wall display would not be practical due to the amount of parallax created by the relatively large distances between successive images. The parallax effect would be particularly noticeable and undesirable with a large display because observers would likely be moving past the viewing port rather than remaining directly in front of it.
The Egging device also uses elements that have a reflective surface, for example, a "partially silvered coating" (column 3, line 20) on one side to reflect images to the viewing port. Such elements reduce the amount of light passing therethrough, thus limiting the number of reflecting elements and their associated images that can be displayed effectively.
U.S. Pat. No. 4,738,522, to Lunde et al., teaches a method and apparatus for coordinated super imposition of images in a visual display. It discloses a method for combining projected images with a three-dimensional, model set. A second set matching the model except for scale is used for live actors and other images. Props used on the second set are blacked out and invisible when photographed.
The actors are taped acting on the second set, and, using a beam splitter, a recorded image is superimposed on the image of the model set to create an illusion that the actors are interacting with the props. Live images of the actors can also be used without being recorded.
U.S. Pat. No. 3,707,115, to Rush, teaches a method for producing a three-dimensional diorama. It discloses a three-dimensional reflective screen upon which is projected a series of images from photographic transparencies. Each image illustrates the same basic exhibit in full color but differing in details. The three-dimensional screen is used as a base for a number of full color, three-dimensional models of differing detail. Each model is photographed from an indexed position. The screen is then stripped of all removable details, and the photographs are projected onto its three-dimensional surface in sequence to illustrate changes in full color of the same basic model.
While each of these displays functions with a certain degree of efficiency, none addresses or solves the problems identified herein relating to the limitations placed on the size and number of images, to the impractical increase in structural size required to increase the size and/or number of images, to the parallax effect, and to the limitations on the number of images due to the reduction of image intensity as light passes through additional coated reflecting surfaces as does the improved multiplanar display system of the present invention as is hereinafter more fully described.